$\begingroup$I have been given the points $(5, 0)$ and $(10, 5)$. I'm also given that the $a$ value in $ax^2 \pm bx \pm c$ is $-1$. I have been trying to work out to how to do this, but, when I graph the parabola, I'm not getting the correct solution.
I've been staring at this problem for a long time, and I'm not certain how to solve it anymore. I'm not very mathematically inclined, so please forgive my naive question.
Thank you.
$\endgroup$1 Answer
$\begingroup$$$y=-x^2+bx+c$$ We know this satisfies $x=5, y=0$ and $x=10,y=5$
$$0=-25+5b+c$$ $$5=-100+10b+c$$
Then you can solve this system of simultaneous equations very easily.
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